| Message ID | 1393381381-30179-1-git-send-email-pingfank@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Wed, Feb 26, 2014 at 10:23:01AM +0800, Liu Ping Fan wrote: > The branch target should be the func addr, not the addr of func_descr_t. > So using ppc_function_entry() to generate the right target addr. > > Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com> > --- > This bug will make ftrace fail to work. It can be triggered when the kernel > size grows up. > --- > arch/powerpc/kernel/ftrace.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c > index 9b27b29..b0ded97 100644 > --- a/arch/powerpc/kernel/ftrace.c > +++ b/arch/powerpc/kernel/ftrace.c > @@ -74,6 +74,7 @@ ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new) > */ > static int test_24bit_addr(unsigned long ip, unsigned long addr) > { > + addr = ppc_function_entry((void *)addr); Won't this break on LE?
On Wed, Feb 26, 2014 at 12:35 PM, Ananth N Mavinakayanahalli <ananth@in.ibm.com> wrote: > On Wed, Feb 26, 2014 at 10:23:01AM +0800, Liu Ping Fan wrote: >> The branch target should be the func addr, not the addr of func_descr_t. >> So using ppc_function_entry() to generate the right target addr. >> >> Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com> >> --- >> This bug will make ftrace fail to work. It can be triggered when the kernel >> size grows up. >> --- >> arch/powerpc/kernel/ftrace.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c >> index 9b27b29..b0ded97 100644 >> --- a/arch/powerpc/kernel/ftrace.c >> +++ b/arch/powerpc/kernel/ftrace.c >> @@ -74,6 +74,7 @@ ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new) >> */ >> static int test_24bit_addr(unsigned long ip, unsigned long addr) >> { >> + addr = ppc_function_entry((void *)addr); > > Won't this break on LE? > How? I can not figure out it. Anyway, ppc_function_entry() is already used in other places with LE. Thx, Fan
On Wed, 2014-02-26 at 10:05 +0530, Ananth N Mavinakayanahalli wrote: > On Wed, Feb 26, 2014 at 10:23:01AM +0800, Liu Ping Fan wrote: > > The branch target should be the func addr, not the addr of func_descr_t. > > So using ppc_function_entry() to generate the right target addr. > > > > Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com> > > --- > > This bug will make ftrace fail to work. It can be triggered when the kernel > > size grows up. > > --- > > arch/powerpc/kernel/ftrace.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c > > index 9b27b29..b0ded97 100644 > > --- a/arch/powerpc/kernel/ftrace.c > > +++ b/arch/powerpc/kernel/ftrace.c > > @@ -74,6 +74,7 @@ ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new) > > */ > > static int test_24bit_addr(unsigned long ip, unsigned long addr) > > { > > + addr = ppc_function_entry((void *)addr); > > Won't this break on LE? ppc_function_entry() just needs to be a nop on LE, as it already is on 32-bit. cheers
On Wed, Feb 26, 2014 at 11:22:16PM +1100, Michael Ellerman wrote:
> ppc_function_entry() just needs to be a nop on LE, as it already is on 32-bit.
Well on LE ABI2, but yes.
Yours Tony
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index 9b27b29..b0ded97 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c @@ -74,6 +74,7 @@ ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new) */ static int test_24bit_addr(unsigned long ip, unsigned long addr) { + addr = ppc_function_entry((void *)addr); /* use the create_branch to verify that this offset can be branched */ return create_branch((unsigned int *)ip, addr, 0);
The branch target should be the func addr, not the addr of func_descr_t. So using ppc_function_entry() to generate the right target addr. Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com> --- This bug will make ftrace fail to work. It can be triggered when the kernel size grows up. --- arch/powerpc/kernel/ftrace.c | 1 + 1 file changed, 1 insertion(+)